/** * The {@code Vector} class implements a growable array of * objects. Like an array, it contains components that can be * accessed using an integer index. However, the size of a * {@code Vector} can grow or shrink as needed to accommodate * adding and removing items after the {@code Vector} has been created. * *
Vector实现了一个可增长的数组集合。如同数组，他可以使用整形索引index来访问元素。然而，vector在创建实例后，可以通过增加和删除元素来增长或减少vector的大小。
Each vector tries to optimize storage management by maintaining a
* {@code capacity} and a {@code capacityIncrement}. The
* {@code capacity} is always at least as large as the vector
* size; it is usually larger because as components are added to the
* vector, the vector's storage increases in chunks the size of
* {@code capacityIncrement}. An application can increase the
* capacity of a vector before inserting a large number of
* components; this reduces the amount of incremental reallocation.
*
*
* should be used only to detect bugs.* *
As of the Java 2 platform v1.2, this class was retrofitted to
* implement the {@link List} interface, making it a member of the
* * Java Collections Framework. Unlike the new collection * implementations, {@code Vector} is synchronized. If a thread-safe * implementation is not needed, it is recommended to use {@link * ArrayList} in place of {@code Vector}.
实现了list接口，称为collection框架的一员，与新的collection不同的是，vector是线程安全的。如果不需要线程安全，建议使用arrayList代替Vector.
多种初始化方式
Vector()：默认容量10，增长0
Vector(size)：容量size，增长0
Vector(size,increaseMount):容量size，增长increaseMount
Vector(new Collection())：使用实现了Collection接口类的实例来初始化。
